The use of solid state scanners in photographic film scanning apparatus is well known. For example, in the CLAS 35 manufactured and sold by Eastman Kodak Company, assignee of the present application, color exposure analysis of film images is performed at a scanner station in which light transmitted through a film strip is focussed onto a linear CCD array by means of optical lenses. The CLAS 35 is a large scale, high speed photographic printer in which the space between the film and the CCD scanner device that is required to accommodate an optical focussing lens system is not of particular concern. In copending commonly assigned application Ser. No. 618,532--Bender et al, filed Nov. 26, 1990, entitled "Exposure Determining Color Film Scanning Apparatus for a Photofinishing System" a solid state scanner is disclosed in which the optical lens system is eliminated and the solid state CCD scanning device is maintained in virtual contact with the film as the film passes through the scanner film gate. By "virtual contact" is meant that the CCD photosites of the scanner are nearly in contact but may be spaced fractionally away from the film image by the housing in which the CCD photosites are enclosed and to avoid physical contact that might damage the film and/or the CCD scanner device. The result of employing virtual contact scanning is a much smaller system suitable for small photographic printers of the minilab and desktop variety.
A concern with the design of a virtual contact scanner of the type described in the above Bender et al application is the need to establish and maintain precise spacing of the CCD arrays from the film image plane. It is typical to mount CCD devices on a printed wiring board which includes the scan control and readout circuits needed to operate the CCD. This requires close control of the manufacturing tolerances on the printed wiring board which is costly and not practical for this application. Additionally, repair and replacement of board mounted scanners can be a problem in terms of maintaining a precise repeatable spacing relationship of the scanner device to the film image plane.
It is therefore an object of this invention to provide a compact, low-cost film scanner apparatus utilizing solid state scanner devices.
It is a further object of the invention to provide for simple and inexpensive mounting of a solid state sensor array in the film gate apparatus of a virtual contact type of scanner in which the spacing of the array from the film image plane is easily and repeatably achieved without the need for intricate adjustments.